Carburetor



oct 29, 1940. F, w, CLOEDY Er AL Re. 21,610

GARBURETOR Original Filed Jan. 6, 1938 Y me Reasued Oct. 29a, 1,940

UNITED sTATEs cAnnUnE'ron Frederick vW. Clocdy, St. Louis, and Harold A. Carlson, University City, Mo., assignors to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Original No. 2,191,905, dated February 27, 1940,

Serial No. 183,604, January 6, 1938. Application for reissue May 25, 1940, Serial No. 331,282

2 Claims.

This invention relates to carburetors for internal combustion engines and consists particularly in novel m'eans for striilizing the fuel metering characteristics thereof.

A well known form of automotive carburetor utilizes a stepped or tapered metering pin associated with the mainy calibrated fuel'metering orifice in the fuel bowl in such a manner as to vary the effective cross sectional area of the' orlflce to supply a richer or leaner fuel and air mixture -according to the demands of the engine. This metering pin may be moved axiallypwith the throttle valve so as to Ireduce the restricting effect upon the metering orifice as the throttle valve is opened, or it may be controlled by a suction device in a manner to increase the open portion of the metering orifice when the suction in the mixture conduit drops. It has been found that the concentricity or eccentricity of the metering pin relative to the metering oriilce has a substantial eil'ect upon the fuel metered therethrough and, accordingly, means should be provided for maintaining the relative position of the pin substantially uniform in this respect. One means of accomplishing this result is illustrated and claimed in a United States Patent No. 1,961,747, issued in the name of William M. Ewart.

One object of the present invention is to provide novel means for maintaining the fuel metering pin in a stable relationship with its metering orifice.

Another object is to provide means for stabilizing the relative position of a fuel metering pin, which means is particularly adaptable for use in carburetors in which the pin Ais controlled by a suction piston or other suction controlled means.

'Ihese objects and other more detailed objects hereafter appearing are attained substantially by the structure illustrated in the accompanying drawing in which Fig. 1 is a side view buretor embodying the invention.

Fig. 2 is a detail horizontal section taken on the corresponding section line of Fig. 1.

Fig. 3 is a detail vertical section taken substantially on the corresponding section line of Fig. 1.

Fig. 4 is a perspective view showing a part of the structure in Fig. 1.

Fig. 5 is a detail view, partly sectioned and v partly in perspective, illustrating a modification and Fig. 6 is a perspective view showing a modified detail asin Fig. 5.

The carburetor in Fig. 1 comprises a downdraft partly sectioned of a car- (Cl. zei-69)' is supplied to the mixture conduit through ay main nozzle 9 opening into the throat portion of the smallest venturi 2 and communicating with the fuel bowl through a calibrated metering orifice member I0. Fuel for idling and low speed operation is supplied through a. passage, shown in part at I I, opening into the mixture conduit through a port I2 adjacent the edge of the throttle valve when closed.

'Formed in the wall of the mixture conduit is a cylinder or chamber I3 communicating through a passage Il with opening I5 into the mixturev conduit posterior to the throttle. Slidable within chamber I3 is a piston I6 having an elongated rod I1 projecting thereabove through cover I8 of the fuel bowl and having at its upper portion a laterally offset arm I9 pinned as at 20 to a metering pin`2I having a stepped lower portion 22 extending into metering orifice member I 0 for varying the effective cross-sectional area. thereof. A

`pair of ribs or wings 23 project laterally from the portion of piston rod I1 Within chamber I3 and are slidable within slots 24 (Fig. 2) to prevent rotation of piston rod l1 and also guide the rod and pin 2l in their longitudinal movements. Due to the lateral offsetting of the actuating rod I1 from the metering pin, this guidingstructure has the effect of maintaining the metering pin substantially uniformly positioned transversely of the metering orifice.

` In Figs. 5 and 6, elongated piston rod member Ila projecting above suction controlled piston Ia has a pair of laterally offset arms 25 for carrying a pair of metering pins 2B, this arrangement being adapted for use in a dual carburetor having a pair of calibrated metering orlce members inthe fuel bowl. Guiding structure Il formed on air inlet horn la slidably receives a closely fitting portion 21 on the upper part of the piston rod for preventing rotation of the rod and maintaining the metering pins uniformly positioned relative to the metering orices.

In both forms, a spring 20 in the suction chamber constantly urges piston lia upwardly of the metering pin into operative relationwith orifice member II to provide a proper mixture when the suction posterior `to the throttle drops below a predetermined value, say three inches of mercury. At other times the metering pin will be drawn down so as to bring a larger portion thereof into the ymetering orifice to provide an economical mixture for nox'n'ial,V part throttle operation. Y

The general features of the carburetor shown, with the exception of the fuel metering mechanism, are well known in the art and do not consaid chamber, a spring arrangedin said cyiindrical`chamber between the piston and the'lower end of said chamber, a piston rod projecting upwardly from said piston and having a :laterally 'oifset portion forming a mounting vfor 'said me- ,tering pin for moving the same parallel to thei/ axisv of said cylinder to vary the effective crosssectional area of said oriiice, non-circular guide means on the wall of said conduit adjacent said piston rod, said piston rod having a non-circular elongated portion extending laterally therefrom maybecalibratedtomovethesmallestpob' and ntting said guide means to prevent rotation of the rod so as to maintain uniform positioning. of said pin mounting .transversely of the axis of said orice, whereby the pin is re-` strained at all `times from misalignment with said orice due to pivotal movement with respect to the wall forming the guide opening.'

2. In a carburetor, a mixing conduit. a part having acallbrated fuelmetering orifice spaced transversely from the wall of said conduit, a guide opening co-axially arranged with respect to said metering orifice, a metering pin having a reduced lower extremity normally extending into saidv orifice, a. cylindrical chamber adjacent,

said conduit communicating at its lower portion with suction in said conduit, a piston in said chamber, a spring arranged in said cylindrical. chamber between they piston and the lower end l\whereby' vsaid metering pin is restrained at all times from disalignmentwith said'orice dueto pivotal movement with respect to the wall forming the guide opening.`l

- FREDERICK W. CLOEDY.

HAROLD A. CARLSON. 

